Heart occlusion devices are used in the medical field for correcting congenital heart defects, such as atrial septal defects (“ASD”), patent foramen ovale (“PFO”) defects, ventricular septal defects (“VSD”), and patent ductus arteriosus (“PDA”) defects. A PFO, illustrated in FIG. 1 at 110, is a persistent, one-way, usually flap-like opening in the wall between the right atrium 102 and left atrium 104 of the heart 100. The foramen ovale 110 serves a desired purpose when a fetus is gestating in utero. Because blood is oxygenated through the umbilical cord and not through the developing lungs, the circulatory system of the fetal heart allows the blood to flow through the foramen ovale as a physiologic conduit for right-to-left shunting. After birth, with the establishment of pulmonary circulation, the increased left atrial blood flow and pressure results in functional closure of the foramen ovale. This functional closure is subsequently followed by anatomical closure of the two over-lapping layers of tissue: septum primum 118 and septum secundum 120.
However, a PFO has been shown to persist in a number of adults. Because left atrial (LA) pressure is normally higher than right atrial (RA) pressure, the flap usually stays closed. Under certain conditions, however, right atrial pressure can exceed left atrial pressure, creating the possibility that blood could pass from the right atrium 102 to the left atrium 104, and blood clots could enter the systemic circulation. It is desirable that this circumstance be eliminated.
The presence of a PFO defect is generally considered to have no therapeutic consequence in otherwise healthy adults. Paradoxical embolism via a PFO defect is considered in the diagnosis for patients who have suffered a stroke or transient ischemic attack (TIA) in the presence of a PFO and without another identified cause of ischemic stroke. While there is currently no definitive proof of a cause-effect relationship, many studies have confirmed a strong association between the presence of a PFO defect and the risk for paradoxical embolism or stroke. In addition, there is significant evidence that patients with a PFO defect who have had a cerebral vascular event are at increased risk for future, recurrent cerebrovascular events.
Accordingly, patients at such an increased risk are considered for prophylactic medical therapy to reduce the risk of a recurrent embolic event. These patients are commonly treated with oral anticoagulants, which potentially have adverse side effects, such as hemorrhaging, hematoma, and interactions with a variety of other drugs. The use of these drugs can alter a person's recovery and necessitate adjustments in a person's daily living pattern.
In certain cases, such as when anticoagulation is contraindicated, surgery may be necessary or desirable to close a PFO defect. The surgery would typically include suturing a PFO closed by attaching septum secundum to septum primum. This sutured attachment can be accomplished using either an interrupted or a continuous stitch and is a common way a surgeon shuts a PFO under direct visualization.
Umbrella devices and a variety of other similar mechanical closure devices, developed initially for percutaneous closure of atrial septal defects (ASDs), have been used in some instances to close PFOs. These devices potentially allow patients to avoid or lessen the side effects often associated with anticoagulation therapies and the risks of invasive surgery. However, umbrella devices and the like that are designed for ASDs may not be optimally suited for use as PFO closure devices.
Certain currently available septal closure devices present possible drawbacks, including technically complex implantation procedures. Additionally, complications are possible due to thrombus, fractures of the components, conduction system disturbances, perforations of heart tissue, and residual leaks. Certain devices have a high septal profile and include large masses of foreign material, which may lead to unfavorable body adaptation of a device. Given that ASD devices are designed to occlude holes, certain of such devices lack anatomic conformability to the flap-like anatomy of PFOs. The flap-like opening of the PFO is complex, and devices with a central post or devices that are self-centering may not close the defect completely, an outcome that is highly desired when closing a PFO defect. Hence, a device with a waist which can conform to the defect will have much higher chance of completely closing the defect. Even if an occlusive seal is formed, the device may be deployed in the heart on an angle, leaving some components insecurely seated against the septum and, thereby, risking thrombus formation due to hemodynamic disturbances. Finally, some septal closure devices are complex to manufacture, which may result in inconsistent product performance.
Certain devices for occluding other heart defects, e.g., ASD, VSD, PDA, also have potential drawbacks. For example, certain currently available devices tend to be either self-centering or non-self-centering and may not properly conform to the intra-cardiac anatomy. Both of these characteristics have distinct advantages and disadvantages. The non-self-centering device may not close the defect completely and may need to be over-sized significantly. This type of device may not be available for larger defects. Further, the self-centering device, if not sized properly, may cause injury to the heart. Some devices have sharp edges, which may damage the heart causing potential clinical problems. Some devices contain too much nitinol/metal, which may cause an undesired reaction in the patient. Some currently marketed devices have numerous model numbers (several available sizes), making it difficult and uneconomical for hospitals and markets to invest in starting a congenital and structural heart interventional program. The present disclosure is designed to address these and other deficiencies of certain existing closure devices.
Devices are also used for occluding other apertures, including uses such as occluding the lumen of a vessel and occluding apertures in vessel walls.
Accordingly, it is desirable to provide improved devices for occluding apertures in tissues or vessels. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background